The processing of human pro-tumor necrosis factor

Human pro-TNF-$\alpha$ is a 26 kd type II transmembrane protein, and it is the precursor of 17 kd mature TNF. Pro-TNF release mature from its extracellular domain by proteolytic cleavage between resideu Ava ($-$1) and Val (+1). Both forms of TNF are biologically active and the native form of mature TNF is a bell-shaped trimer. The structure of pro-TNF was studied both in intact cell system and in an in vitro translation system by chemical crosslinking. We found that human pro-TNF protein exist as a trimer in intact cells (LPS-induced THP-1 cells and TNF cDNA transfected COS-3 cells) and this trimeric structure is assembled intracellularly, possibly in the ER. By analysis several deletion mutants, we observed a correlation between expression of pro-TNF cytotoxicity in a juxtacrine fashion and detection of the trimer, suggesting the trimeric structure is very important for its biologic activity. With a series of deletion mutants in the linking domain, we found that the small deletion did not block the cleavage and large deletion did regardless of the presence or absence of the native cleavage site, suggesting that the length of the residues between the plasma membrane and the base of the trimer determines the rate of the cleavage, possibly by blocking the accessibility of the cleavage enzyme to its action site. Our data also suggest that the native cleavage site is not sufficient for the release of mature TNF and alternative cleavage site(s) exists. ^

Chromatin structure and DNase I hypersensitivity in the transcriptionally active and inactive porcine tumor necrosis factor gene locus

We have analyzed the chromatin structure of the porcine tumor necrosis factor gene locus (TNF-alpha and TNF-beta). Nuclei from porcine peripheral blood mononuclear cells were digested with different nucleases. As assessed with micrococcal nuclease, the two TNF genes displayed slightly faster digestion kinetics than bulk DNA. Studies with DNaseI revealed distinct DNaseI hypersensitive sites (DH-sites) within the porcine TNF locus. Four DH-sites could be observed in the promoter and mRNA leader regions of the TNF-beta gene. Two DH-sites could be observed for the TNF-alpha gene, one located in the promoter region close to the TATA-box and the other site in intron 3. This pattern of DH-sites was present independently of the activation state of the cells. Interestingly in a porcine macrophage-like cell line, we found that the TNF-alpha promoter DH-site disappeared and another DH-site appeared in the region of intron 1. Additionally, the DH-site of intron 3 could be enhanced by PMA-stimulation in these cells. TNF-beta sites were not detected in this cell line. However, DH-sites were totally absent in fibroblasts (freshly isolated from testicles) and in porcine kidney cells (PK15 cell line) both of which do not transcribe the TNF genes. Therefore, the pattern of DH-sites corresponds to the transcriptional activity of analyzed cells.

The porcine tumor necrosis factor-encoding genes: sequence and comparative analysis

We have cloned and sequenced a 10.22-kb fragment of the genomic locus of the porcine tumor necrosis factor-encoding genes, TNF-alpha and TNF-beta. A liver genomic DNA library, partially digested with Sau3AI, was cloned into the phage lambda EMBL4 and screened with a porcine TNF-alpha cDNA probe. Analysis showed that both the TNF-alpha and TNF-beta genes were present on the cloned fragment. In addition, the cloned fragment contained about 2 kb of repetitive sequences 5' to the TNF-beta gene. The TNF genes are arranged in a tandem repeat, as is the case for the human, mouse and rabbit TNF genes. The comparison of both genes with their human homologues displayed a considerable degree of conservation (80%), suggesting an equal evolution rate.

Unimpaired autoreactive T-cell traffic within the central nervous system during tumor necrosis factor receptor-mediated inhibition of experimental autoimmune encephalomyelitis.

The critical role of tumor necrosis factor (TNF) as a mediator in autoimmune inflammatory processes is evident from in vivo studies with TNF-blocking agents. However, the mechanisms by which TNF, and possibly also its homologue lymphotoxin alpha, contributes to development of pathology in rheumatoid arthritis and Crohn disease and in animal models like experimental autoimmune encephalomyelitis is unclear. Possibilities include regulation of vascular adhesion molecules enabling leukocyte movement into tissues or direct cytokine-mediated effector functions such as mediation of tissue damage. Here we show that administration of a TNF receptor (55 kDa)-IgG fusion protein prevented clinical signs of actively induced experimental autoimmune encephalomyelitis. Significantly, the total number of CD4+ T lymphocytes isolated from the central nervous system of clinically healthy treated versus diseased control animals was comparable. By using a CD45 congenic model of passively transferred experimental autoimmune encephalomyelitis to enable tracking of myelin basic protein-specific effector T lymphocytes, prevention of clinical signs of disease was again demonstrated in treated animals but without quantitative or qualitative impediment to the movement of autoreactive T lymphocytes to and within the central nervous system. Thus, despite the uninterrupted movement of specific T lymphocytes into the target tissue, subsequent disease development was blocked. This provides compelling evidence for a direct effector role of TNF/lymphotoxin alpha in autoimmune tissue damage.

Tumor necrosis factor-induced apoptosis is mediated by a CrmA-sensitive cell death pathway.

We report here that the activation of the interleukin 1 beta (IL-1 beta)-converting enzyme (ICE) family is likely to be one of the crucial events of tumor necrosis factor (TNF) cytotoxicity. The cowpox virus CrmA protein, a member of the serpin superfamily, inhibits the enzymatic activity of ICE and ICE-mediated apoptosis. HeLa cells overexpressing crmA are resistant to apoptosis induced by Ice but not by Ich-1, another member of the Ice/ced-3 family of genes. We found that the CrmA-expressing HeLa cells are resistant to TNF-alpha/cycloheximide (CHX)-induced apoptosis. Induction of apoptosis in HeLa cells by TNF-alpha/CHX is associated with secretion of mature IL-1 beta, suggesting that an IL-1 beta-processing enzyme, most likely ICE itself, is activated by TNF-alpha/CHX stimulation. These results suggest that one or more members of the ICE family sensitive to CrmA inhibition are activated and play a critical role in apoptosis induced by TNF.

Secretion of tumor necrosis factor by human leukocytes stimulated with shark cartilage

To assess the role of shark cartilage as an immune modulator, acid, salt-soluble, and phosphate-buffered saline extracts were prepared from three different commercial sources (SL, TL, FDC) of cartilage and used to stimulate human leukocytes in vitro. Duplicate leukocyte cultures were set up, each containing 50 $\mu$l of endotoxin-free extract, 200 $\mu$l of cell suspension (2.4-2.5 $\times$ 10$\sp5$ cells) and 100 $\mu$l of medium and incubated at 37$\sp\circ$C. Cultures stimulated with LPS (5 $\mu$g/ml) or medium served as the positive and negative controls, respectively. Culture supernatants were assayed for TNF$\alpha$ by ELISA. Cartilage extracts stimulated cells to release significant levels of TNF$\alpha$ (p $<$.005); the highest response was obtained with the acid extract of SL cartilage. In comparison, response to corresponding extracts of bovine cartilage was lower (p $<$.05). The stimulatory activity was reduced (85%) following proteolytic digestion, and lost when extract was heated (60$\sp\circ$C, 20 min) or treated with urea (6M), suggesting that the active component(s) is a protein. ^

Distribution of interleukin-2,-4,-10, tumour necrosis factor-alpha and transforming growth factor-beta mRNAs in oral lichen planus

In the present study. MRNA for the cytokines interleukin-2 (IL-2), IL-4, IL-10 tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor beta-1 (TGF-beta-1) were investigated in oral lichen planus (OLP) lesions using in situ hybridization with S-35-labelled oligonucleotide probes on frozen tissue sections. In addition, the expression of interferon-gamma (IFN-gamma), IL-10 and IL-4 mRNAs was analysed in cultured lesional T lymphocytes from oral lichen planus by polymerase chain reaction. Cells expressing mRNA for IL-2, IL-4, IL-10, TNF-alpha and TGF-beta(1) were found in all the biopsies studied. Approximately 1-2% of the total number of infiltrating cells in the lesions were positive for each of the different cytokine mRNAs. Most biopsies contained basement membrane-oriented, mRNA-positive cells. In the cultured T-cell lines, message for IFN-gamma was detected in all the patients, IL-10 in all but one, and IL-4 in just one of the seven patients investigated. The results suggest that mRNA for both pro- and anti-inflammatory cytokines, i.e., mixed T-helper 1 (T(H)1) and T(H)2 cytokine profiles, are generated simultaneously by a limited number of cells in chronic lesions of OLP. (C) 1999 Elsevier Science Ltd. All rights reserved.

Tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis of human melanoma is regulated by Smac/DIABLO release from mitochondria

In previous studies we have shown that the sensitivity of melanoma cell lines to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)induced apoptosis was determined largely by the level of expression of death receptor TRAIL receptor 2 on the cells. However, approximately one-third of melanoma cell lines were resistant to TRAIL, despite expression of high levels of TRAIL receptor 2. The present studies show that these cell lines had similar levels of TRAIL-induced activated caspase-3 as the TRAIL-sensitive lines, but the activated caspase-3 did not degrade substrates downstream of caspase-3 [inhibitor of caspase-activated DNase and poly(ADP-ribose) polymerase]. This appeared to be due to inhibition of caspase-3 by X-linked inhibitor of apoptosis (XIAP) because XIAP was bound to activated caspase-3, and transfection of XIAP into TRAIL-sensitive cell lines resulted in similar inhibition of TRAIL-induced apoptosis. Conversely, reduction of XIAP levels by overexpression of Smac/ DIABLO in the TRAIL-resistant melanoma cells was associated with the appearance of catalytic activity by caspase-3 and increased TRAIL-induced apoptosis. TRAIL was shown to cause release of Smac/DIABLO from mitochondria, but this release was greater in TRAIL-sensitive cell lines than in TRAIL-resistant cell lines and was associated with downregulation of XIAP levels. Furthermore, inhibition of Smac/DIABLO release by overexpression of Bcl-2 inhibited down-regulation of XIAP levels. These results suggest that Smac/DIABLO release from mitochondria and its binding to XIAP are an alternative pathway by which TRAIL induces apoptosis of melanoma, and this pathway is dependent on the release of activated caspase-3 from inhibition by XIAP and possibly other inhibitor of apoptosis family members.

Early Australian experience with infliximab, a chimeric antibody against tumour necrosis factor-alpha, in the treatment of Crohn's disease: is its efficacy augmented by steroid-sparing immunosuppressive therapy?

Background: Tumour necrosis factor-alpha (TNF-alpha) plays an important role in the pathology of Crohn's disease. Infliximab, a chimeric antibody against TNF-alpha, has been shown in controlled clinical trials to be effective in two-thirds of patients with refractory or fistulating Crohn's disease. The factors that determine a clinical response in some patients but not others are unknown. Aims: To document the early Australian experience with infliximab treatment for Crohn's disease and to identify factors that may determine a beneficial clinical response. Methods: Gastroenterologists known to have used infliximab for Crohn's disease according to a compassionate use protocol were asked to complete a spreadsheet that included demographic information, Crohn's disease site, severity, other medical or surgical treatments and a global clinical assessment of Crohn's disease outcome, judged by participating physicians as complete and sustained (remission for the duration of the study), complete but unsustained (remission at 4 weeks but not for the whole study) or partial clinical improvement (sustained or unsustained). Results: Fifty-seven patients were able to be evaluated, with a median follow-up time of 16.4 (4-70) weeks, including 23 patients with fistulae. There were 21 adverse events, including four serious events. Fifty-one patients (89%) had a positive clinical response for a median duration (range) of 11 (2-70) weeks. Thirty patients (52%) had a remission at 4 weeks, 10 of whom had remission for longer than 12 weeks. Forty-two per cent of fistulae closed. Sustained remission (P = 0.065), remission at 4 weeks (P = 0.033) and a positive clinical response of any sort (P = 0.004) were more likely in patients on immunosuppressive therapy, despite there being more smelters in this group. Conclusion: This review of the first Australian experience with infliximab corroborates the reported speed and efficacy of this treatment for Crohn's disease. The excellent response appears enhanced by the concomitant use of conventional steroid-sparing immunosuppressive therapy.

Presence of Circulating Levels of Interferon-g, Interleukin-10 and Tumor Necrosis Factor-a in Patients with Visceral Leishmaniasis

Experimental murine L. major infection is characterized by the expansion of distinct CD4+ T cell subsets. The Th1 response is related to production of IFN-g and resolution of infection, whereas Th-2 response with production of IL-4 and IL-10 and dissemination of infection. The objective of this study was to measure the circulating levels of IFN-g, IL-10 and TNF-a in patients with visceral leishmaniasis (VL) before, during and at the end of therapy and to examine the association between cytokine levels and activity of VL. Fifteen patients with VL were evaluated. The cytokine determinations were done by using the enzyme-linked immunoassay (ELISA) before, during and at the end of therapy. At baseline, we detected circulating levels of IFN-g in 13 of 15 patients (median = 60 pg/ml); IL-10 in 14 of 15 patients (median = 141.4 pg/ml); and TNF-a in 13 of 14 patients (median = 38.9 pg/ml). As patients improved, following antimonial therapy, circulating levels of IL-10 showed an exponential decay (y = 82.34 e–0,10367x, r = –0.659; p < 0.001). IFN-g was no longer detected after 7/14 days of therapy. On the other hand, circulating levels of TNF-a had a less pronounced decay with time on therapy, remaining detectable in most patients during the first seven days of therapy (y = 36.99-0.933x, r = –0.31; p = 0.05). Part of the expression of a successful response to therapy may, therefore, include reduction in secretion of inflammatory as well as suppressive cytokines. Since IL-10 and IFN-g are both detected prior to therapy, the recognized cellular immune depression seen in these patients may be due to biological predominance of IL-10 (type 2 cytokine), rather than lack of IFN-g (type 1 cytokine) production.

Glucocorticoid-induced tumor necrosis factor receptor expression in patients with cervical human papillomavirus infection

Introduction The progression of human papillomavirus (HPV) infection in the anogenital tract has been associated with the involvement of cells with regulatory properties. Evidence has shown that glucocorticoid-induced tumor necrosis factor receptor (GITR) is an important surface molecule for the characterization of these cells and proposes that GITR ligand may constitute a rational treatment for many cancer types. We aimed to detect the presence of GITR and CD25 in cervical stroma cells with and without pathological changes or HPV infection to better understand the immune response in the infected tissue microenvironment. Methods We subjected 49 paraffin-embedded cervical tissue samples to HPV DNA detection and histopathological analysis, and subsequently immunohistochemistry to detect GITR and CD25 in lymphocytes. Results We observed that 76.9% of all samples with high GITR expression were HPV-positive regardless of histopathological findings. High GITR expression (77.8%) was predominant in samples with ≥1,000 RLU/PCB. Of the HPV-positive samples negative for intraepithelial lesion and malignancy, 62.5% had high GITR expression. High GITR expression was observed in both carcinoma and high-grade squamous intraepithelial lesion (HSIL) samples (p = 0.16). CD25 was present in great quantities in all samples. Conclusions The predominance of high GITR expression in samples with high viral load that were classified as HSIL and carcinoma suggests that GITR+ cells can exhibit regulatory properties and may contribute to the progression of HPV-induced cervical neoplasia, emphasizing the importance of GITR as a potential target for immune therapy of cervical cancer and as a disease evolution biomarker.

Anti-tumor necrosis factor drug survival in axial spondyloarthritis is independent of the classification criteria.

To compare the impact of meeting specific classification criteria [modified New York (mNY), European Spondyloarthropathy Study Group (ESSG), and Assessment of SpondyloArthritis international Society (ASAS) criteria] on anti-tumor necrosis factor (anti-TNF) drug retention, and to determine predictive factors of better drug survival. All patients fulfilling the ESSG criteria for axial spondyloarthritis (SpA) with available data on the axial ASAS and mNY criteria, and who had received at least one anti-TNF treatment were retrospectively retrieved in a single academic institution in Switzerland. Drug retention was computed using survival analysis (Kaplan-Meier), adjusted for potential confounders. Of the 137 patients classified as having axial SpA using the ESSG criteria, 112 also met the ASAS axial SpA criteria, and 77 fulfilled the mNY criteria. Drug retention rates at 12 and 24 months for the first biologic therapy were not significantly different between the diagnostic groups. Only the small ASAS non-classified axial SpA group (25 patients) showed a nonsignificant trend toward shorter drug survival. Elevated CRP level, but not the presence of bone marrow edema on magnetic resonance imaging (MRI) scans, was associated with significantly better drug retention (OR 7.9, ICR 4-14). In this cohort, anti-TNF drug survival was independent of the classification criteria. Elevated CRP level, but not positive MRI, was associated with better drug retention.

Treatment with tumor necrosis factor inhibitors in axial spondyloarthritis: comparison between private rheumatology practices and academic centers in a large observational cohort.

OBJECTIVE: To evaluate the initiation of and response to tumor necrosis factor (TNF) inhibitors for axial spondyloarthritis (axSpA) in private rheumatology practices versus academic centers. METHODS: We compared newly initiated TNF inhibition for axSpA in 363 patients enrolled in private practices with 100 patients recruited in 6 university hospitals within the Swiss Clinical Quality Management (SCQM) cohort. RESULTS: All patients had been treated with ≥ 1 nonsteroidal antiinflammatory drug and > 70% of patients had a baseline Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) ≥ 4 before anti-TNF agent initiation. The proportion of patients with nonradiographic axSpA (nr-axSpA) treated with TNF inhibitors was higher in hospitals versus private practices (30.4% vs 18.7%, p = 0.02). The burden of disease as assessed by patient-reported outcomes at baseline was slightly higher in the hospital setting. Mean levels (± SD) of the Ankylosing Spondylitis Disease Activity Score were, however, virtually identical in private practices and academic centers (3.4 ± 1.0 vs 3.4 ± 0.9, p = 0.68). An Assessment of SpondyloArthritis international Society (ASAS40) response at 1 year was reached for ankylosing spondylitis in 51.7% in private practices and 52.9% in university hospitals (p = 1.0) and for nr-axSpA in 27.5% versus 25.0%, respectively (p = 1.0). CONCLUSION: With the exception of a lower proportion of patients with nr-axSpA newly treated with anti-TNF agents in private practices in comparison to academic centers, adherence to ASAS treatment recommendations for TNF inhibition was equally high, and similar response rates to TNF blockers were achieved in both clinical settings.

Comparison of drug survival rates for tumor necrosis factor antagonists in rheumatoid arthritis.

BACKGROUND Persistence of anti-tumor necrosis factor (TNF) therapy in rheumatoid arthritis (RA) is an overall marker of treatment success. OBJECTIVE To assess the survival of anti-TNF treatment and to define the potential predictors of drug discontinuation in RA, in order to verify the adequacy of current practices. DESIGN An observational, descriptive, longitudinal, retrospective study. SETTING The Hospital Clínico Universitario de Valladolid, Valladolid, Spain. PATIENTS RA patients treated with anti-TNF therapy between January 2011 and January 2012. MEASUREMENTS Demographic information and therapy assessments were gathered from medical and pharmaceutical records. Data is expressed as means (standard deviations) for quantitative variables and frequency distribution for qualitative variables. Kaplan-Meier survival analysis was used to assess persistence, and Cox multivariate regression models were used to assess potential predictors of treatment discontinuation. RESULTS In total, 126 treatment series with infliximab (n = 53), etanercept (n = 51) or adalimumab (n = 22) were administered to 91 patients. Infliximab has mostly been used as a first-line treatment, but it was the drug with the shortest time until a change of treatment. Significant predictors of drug survival were: age; the anti-TNF agent; and the previous response to an anti-TNF drug. LIMITATION The small sample size. CONCLUSION The overall efficacy of anti-TNF drugs diminishes with time, with infliximab having the shortest time until a change of treatment. The management of biologic therapy in patients with RA should be reconsidered in order to achieve disease control with a reduction in costs.